the assessment of usability of electronic shopping: a heuristic

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International Journal of Information Management 25 (2005) 516–532

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The assessment of usability of electronic shopping:A heuristic evaluation

Sherry Y. Chen�, Robert D. Macredie

School of Information Systems, Computing and Mathematics, Brunel University, Uxbridge, Middlesex UB8 3PH, UK

Abstract

Today there are thousands of electronic shops accessible via the Web. Some provide user-friendly features whilst others

seem not to consider usability factors at all. Yet, it is critical that the electronic shopping interface is user-friendly so as to

help users to obtain their desired results. This study applied heuristic evaluation to examine the usability of current

electronic shopping. In particular, it focused on four UK-based supermarkets offering electronic services: including

ASDA, Iceland, Sainsbury, and Tesco. The evaluation consists of two stages: a free-flow inspection and a task-based

inspection. The results indicate that the most significant and common usability problems have been found to lie within the

areas of ‘User Control and Freedom’ and ‘Help and Documentation’. The findings of this study are applied to develop a

set of usability guidelines to support the future design of effective interfaces for electronic shopping.

r 2005 Elsevier Ltd. All rights reserved.

Keywords: Electronic commerce; Usability evaluation; Interface evaluation; Web-based application

1. Introduction

With the widespread use of the World Wide Web (Web), users are increasingly interfacing to, andinteracting with, web-based applications. Among a variety of Web-based applications, electronic shopping is afairly recent phenomenon. Although there are thousands of electronic shops on the Web today, the majority ofthese are only a few years old (Helander & Khalid, 2000). In traditional shopping, the interaction betweenusers and the physical shop determines the impression that the users have of the shop. However, in electronicshopping the Web site may be thought of as a ‘window’ through which users have their initial interaction withthe shop (Zhang & von Dran, 2002) and the design of which presents the users with a comprehensive image ofthe shop (Tung, 2001). In other words, the Web site formulates the working environment of electronic shops,so it is critical that the working environment is user-friendly in order to help users to achieve the desired results(Despotopoulos, Korinthios, Nasios, & Reisis, 1999). As such, usability evaluation of web-based electronicshopping becomes paramount because it can provide concrete prescriptions for developing user-centredelectronic shops that might be expected to increase user uptake and the volume of sales achieved by aligning tousers’ needs.

e front matter r 2005 Elsevier Ltd. All rights reserved.

nfomgt.2005.08.008

ing author. Tel.: +44 1895 266023; fax: +44 1895 251686.

ess: [email protected] (S.Y. Chen).

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ARTICLE IN PRESSS.Y. Chen, R.D. Macredie / International Journal of Information Management 25 (2005) 516–532 517

However, existing research has not paid much attention to evaluating the usability of electronic shopping(Benbunan-Fich, 2001). In this vein, the study reported in this paper aims to assess key elements of theinterface design of electronic shopping. In particular, this study will focus on a specific genre of electronicshops, electronic supermarkets, which are more challenging in current electronic shopping because manyinterface elements need to be considered (See Section 3.4 for details). Among the various usability inspectiontechniques, the primary technique used in this study is heuristic evaluation, which involves each interface beingscrutinised against a set of recognised usability principles, or the ‘heuristics’ (Nielsen & Molich, 1990). Anumber of studies have proven the easy adaptability of this approach to the evaluation of the design of Websites (Nielsen & Norman, 2000). This study belongs to this category. In addition, this technique allows adetailed evaluation of the whole interface and ensures that the entire problem space is covered. Research hasshown that problems overlooked in user testing can be in fact identified through heuristic evaluation. Yet,there is a clear lack of empirical studies that apply such criteria to evaluate electronic shops, and this is wherethis study seeks to make a contribution.

The paper begins by building a theoretical background to present the importance of usability inspection inthe development of electronic shopping. It then progresses to discuss an empirical study, assessing theinterface design of electronic shopping using Nielsen’s heuristics (1994). Subsequently, the findings of thisempirical study are used to develop a set of usability guidelines, which can work as a checklist to help designersto judge the values of different interface features with respect to electronic shopping, and can provide guidancefor future usability improvements in this and other web-based applications.

2. Theoretical background

2.1. Electronic shopping

The rapid proliferation of the Internet and the Web has created a fast growing channel for electronicshopping. Electronic shopping is a major component of the business-to-consumer (b-2-c) category ofelectronic commerce (Elliot & Fowell, 2000), which is associated with the buying and selling of information,products, and services via the Web (Kalakota & Whinston, 1996). The benefits of electronic shopping are wellknown. Grewal, Iyer, Krishnan, and Sharma (1999) claim that electronic shopping can provide an extremelyhigh level of convenience for those whose time costs are perceived to be too high to invest in conventionalshopping. Other incentives for consumers to use electronic shopping include broader selections (Jarvenpaa &Todd, 1997), competitive pricing, and greater access to information (Peterson, Balasubramanian, &Bronnenberg, 1997). A study by Kehoe, Pikow, and Rogers (1998) indicated that for about 40% of therespondents, electronic shopping was their primary use of the web. This suggests that electronic shopping hasgained considerable appeal during the past few years.

However, the success rates of using electronic shopping are only 56% (Nielsen, 2001). Service quality hasbeen found to be one of the most important factors for the success of electronic shopping (Kim & Lee, 2002).One of the challenges of service quality in electronic shopping is Web design and a growing number of studiesare examining customer expectations in relation to Web design (Romano, 2001). Jarvenaa and Todd (1997)found ‘shopping experience’ and ‘product perception’ to be especially important and there is a proportionatedissatisfaction with navigation when seeking to locate specific items. Kirakowski, Claridge, and Whitehand(1998) found that the important factors influencing a customer’s perception include ‘attractiveness’, ‘control’,‘efficiency’ and ‘helpfulness’. A similar study by Wolfinbarger and Gilly (2000) found that the majority of on-line buyers are motivated by design features that increase their sense of ‘control’ and ‘freedom’, includingorder tracking, purchase histories, savings information, optional e-mail notification and special deals. Thesestudies suggest that the usability of Web design has significant effects on users’ satisfaction in relation toservice quality (Bouch, Kuchinsky, & Bhatti 2000).

Failure to provide effective design may also have a serious economic impact. For example, Nielsen (2001)found that electronic shops lose half of their potential sales because of poor usability. Liang and Lai (2000),who studied the quality of web design and analysed consumer choices, found that design quality significantlyaffected consumer choice of electronic stores. In addition, Hurst (2000) showed that 39% of shoppers failed intheir buying attempts because the sites were too difficult to use. Similarly, Tilson, Dong, Martin, and Kieche

ARTICLE IN PRESSS.Y. Chen, R.D. Macredie / International Journal of Information Management 25 (2005) 516–532518

(1998a) asked users to rate 40 listed items in terms of their effects on the decision to purchase. In the list of thetop seven concerns, four items were pertinent to the usability of the interface design: feedback to confirm thatthe order has been received; the ability to go back and edit the purchase order list; having order buttons thatare clear and easy to find; and knowing which category or section of the site to look in to find the productwanted. Another study by Tilson, Dong, Martin, and Kieke (1998b) indicates that the usability problems ofelectronic shops become serious, and these problems resulted in users failing to find what they were lookingfor, or even abandoning the purchase though they had found the relevant product. Scott (2000) concluded that‘Cyber shopping’ would not become widespread until screen design and content structure had been improved.

The aforementioned evidence suggests that the usability of Web design is a key factor in determining thesuccess of electronic shopping. Electronic shopping will not be fully accepted by users until usability issueshave been addressed in sufficient detail to inform interface design. It seems clear that designing electronicshops with an effective user interface has an important impact on users’ attitudes to their use. Ultimately, easeof use and the presence of user-friendly features can determine whether a user frequently returns and usesparticular electronic shop. Hence, there is a need to conduct usability inspection of current electronic shoppingin order to increase user satisfaction and the purchase of the products as well.

2.2. Usability inspection

Usability is a very broad concept in system design (Lee, 1999). Basically, it is concerned with designingsoftware applications which people find convenient and practicable for use (Nielsen, 1993) and is often definedas a measure related to how usable or user-friendly the product, service, or system is (Flowers, 2000). Informative evaluation, usability is mostly concerned with evaluating the software interface using approachesknown as usability inspections or expert reviews (Nielsen & Mack, 1994). Major techniques of usabilityinspections include:

�
Heuristic evaluation—examination of a user interface based on specific rules (Wild & Macredie, 2000); � Cognitive walkthrough—an usability evaluation method based on cognitive theory (Rieman, Franzke, &
Redmiles, 1995);
� User testing—evaluation that involves users to assess usability issues (Conyer, 1995).
Among these techniques, heuristic evaluation is the most rapid, cheap, and effective way for identifyingusability problems (Greenberg, Fitzpatrick, Gutwin, & Kaplan, 2000), and involves an expert evaluating theinterface against a set of recognised usability principles—the ‘heuristics’ (Nielsen, 1994b). Heuristic evaluationwas first formally described in presentations in the Human–Computer Interaction conference through paperspublished by Nielson and Molich (1990). Since then, they have refined the heuristics based on a factor analysisof 249 usability problems (Nielsen, 1994a) to derive a revised set of heuristics with maximum explanatorypower. Table 1 presents the detail of the revised set of 10 heuristics (H).

The advantages of heuristic evaluation are reflected by its commercial and industrial applications. Referredto as a ‘discount usability engineering method’, it is certainly cheap but also fast, easy to learn, flexible, andmost importantly effective (Nielsen, 1997). Although heuristic evaluation falls into the category of ‘expertreview’, it can be used effectively by both novices and experts. Ideally, an evaluator should have a broadbackground in usability evaluation and interface design as well as specific knowledge of the subject domain.However, it is also true that heuristic evaluation techniques provide little difficulty to those who want to usethem, regardless of their prior knowledge in usability evaluation and subject domain. In fact, it is possible touse heuristic evaluation after only a few hours of training (Nielsen, 1995). The prescription of structuredtechniques can also facilitate effective evaluation by novices, more so than for other usability methodsavailable (Levi & Conrad, 1996).

The other advantage of heuristic evaluation is that it can be used to address some of the gaps in pastresearch into interface design, which either focused on a particular aspect of interface design in detail orconsidered the entire interface without enough depth (Baker, Greenberg, & Gutwin, 2001). The use ofheuristics ensures both that the interface can be evaluated in depth and that the overarching and specificproblems can be discovered. Fu, Salvendy, & Turley (2002) applied heuristic evaluation and user testing to

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Table 1

Nielsen’s ten heuristics (1994b)

Heuristics Explanations

H1: Visibility of system status The system should always keep user informed about what is going on by providing

appropriate feedback within reasonable time

H2: Match between system and the real

world

The system should speak the user’s language, with words, phrases and concepts familiar to

the user, rather than system-oriented terms. Follow real-world conventions, making

information appear in a natural and logical order

H3: User control and freedom Users should be free to develop their own strategies, select and sequence tasks, and undo

and redo activities that they have done, rather than having the system do these for them

H4: Consistency and standards Users should not have to wonder whether different words, situations, or actions mean the

same thing and the system should follow platform conventions

H5: Error prevention Even better than good error messages is a careful design, which prevents a problem from

occurring in the first place

H6: Recognition rather than recall Make objects, actions, and options visible. The users should not have to remember

information from one part of the dialogue to another. Instructions for use of the system

should be visible or easily retrievable whenever appropriate

H7: Flexibility and efficiency of use Allow users to tailor frequent actions. Provide alternative means of access and operation

for users who differ from the ‘‘average’’ user (e.g., physical or cognitive ability, culture,

language, etc.)

H8: Aesthetic and minimalist design Dialogues should not contain information that is irrelevant or rarely needed. Every extra

unit of information in a dialogue competes with the relevant units of information and

diminishes their relative visibility

H9: Help users recognise, diagnose and

recover from errors

Error messages should precisely indicate the problem and constructively suggest a

solution. They should be expressed in plain language

H10: Help and documentation Even though it is better if the system can be used without documentation, it may be

necessary to provide help and documentation. Any such information should be easy to

search, focused on the user’s task, list concrete steps to be carried out, and not be too large

S.Y. Chen, R.D. Macredie / International Journal of Information Management 25 (2005) 516–532 519

assess the user interface of an Internet-based multimedia information application. There were 39 usabilityproblems identified. The heuristic evaluation found a larger number of problems (n ¼ 34) than user testing.This practical value of heuristic evaluation is also reflected in the study by Jeffries, Miller, Wharton, andUyeda (1991) who compared four different techniques used to evaluate a user interface for a software productprior to its release. The four techniques were heuristic evaluation, software guidelines, cognitive walkthroughs,and user testing. Overall, heuristic evaluations identified the most usability problems, reporting one-third ofthe most severe problems and two-thirds of the least severe. These serious problems found by heuristicevaluation required the least amount of effort to uncover; leading Jefferies et al. (1991) to claim that heuristicevaluation had a distinct cost advantage.

3. Methodology design

3.1. Conceptual framework

Having demonstrated the potential of heuristic evaluation, this study applies it to assess the interface designof current electronic shopping sites. A conceptual framework of this study is provided in Fig. 1. The sectionsbelow describe each of the stages outlined in the framework. In the first stage, an existing set of heuristics(Nielsen, 1994a,b) was extended to include three new heuristics (Section 3.2). Subsequently, a set of evaluationcriteria was developed for each heuristic to be used as a checklist for the evaluation sessions (Section 3.3). Forthe research instruments, electronic supermarkets were selected for the category of electronic shops to beevaluated (Section 3.4). The evaluation sessions comprised two stages: a free-flow inspection and a task-basedinspection (Section 3.5). Once the evaluations had been completed, severity ratings were assigned to each ofthe criteria to indicate the seriousness of each interface’s usability problems. Finally, the data collated from the

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Fig. 1. Conceptual framework.

S.Y. Chen, R.D. Macredie / International Journal of Information Management 25 (2005) 516–532520

evaluations were analysed (Section 4), and the findings were used to develop a set of new usability guidelinesfor the future design of effective and usable electronic shopping interfaces (Section 5).

3.2. Extension of heuristics

Nielsen’s (1994b) set of heuristics was used as a benchmark in this study, as their usefulness has already beenstudied and validated (e.g. Kahn & Prail, 1994). The most widely used and regarded set of heuristics adoptedfor usability inspections are those proposed in 1990 and last revised in 1994. Since the revision was done 10years ago, it is necessary to extend Nielsen’s existing heuristics to address current needs. In addition, Nielsen’sheuristics are notably ‘product-oriented’ (Floyd, 1997). In terms of assessment/evaluation, they treat systemsas self-contained objects, which largely marginalizes the humanistic aspects of systems. To make up for thisshortcoming, this study also considered three additional heuristics selected from Muller et al.’s (1995) andMuller, Matheson, Page, and Gallup’s (1998) Participatory Heuristic Evaluation, which take a ‘process-oriented’ perspective and place emphasis on the fit of the system to users and their work needs. The maindifference between the product-oriented and the process-oriented paradigm is that the former focuses on thesystem itself whereas the latter emphasises on the human work process that the system is intended to support.Finding from recent studies in software engineering (e.g., Floyd, 1997), usability inspection (e.g., Catani andBiers, 1998) and web user experience (e.g., Hoffman and Novak, 1996) suggest that both paradigms areimportant and that there is a need to find a balance between them. This is also the reason why the additionalheuristics were adapted for use in this study. The details of the additional heuristics are presented in Table 2.

3.3. Development of evaluation criteria

The set of heuristics, although very useful, was only suitable as general usability guidelines that could beused as a broad framework for evaluation. They did not prescribe a step-by-step or pragmatic approach thatcould be closely followed in usability inspections. If used in isolation, only general usability problems could beidentified. To facilitate a detailed, structured and thorough evaluation of each interface, it was necessary todevelop associated criteria for each heuristic. The criteria were developed by an analysis of past and presentusability studies (e.g. Pierotti, 1995; Nielsen & Mack, 1994). The findings of these studies were applied toidentify which interface elements might affect users’ performance or cause difficulties in interacting with thesystem, and such interface elements were extracted to develop the criteria, which were then classified intosuitable heuristics based on their characteristics.

In the set of criteria, each criterion developed referred to a requirement for a specific interface feature orelement that should be adhered to and was mapped onto a detailed checklist which was used for the usability

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Table 2

Additional heuristics (Adapted from Muller et al., 1998)

Heuristics Explanations

H11: Support and extend the user’s

current skills

The system should support, extend, supplement, or enhance the user’s skills, background

knowledge, and expertise and not replace them

H12: Pleasurable and respectful

interaction with the user

The user’s interactions with the system should enhance the quality of her or his work-life.

The user should be treated with respect. The design should be aesthetically pleasing—with

artistic as well as functional value

H13: Protect the personal information The system should help the user to protect personal or private information—belonging to

the user or the his/her clients


inspections to examine the interface design of the electronic supermarkets. The advantage of using the detailedchecklist was that the maximum number of usability problems could be identified for each interface.Furthermore, the provision of the detailed checklist helped ensure that during the heuristic evaluationsessions, the usability problems identified could be abstracted down to the lowest levels of detail. The checklistapproach facilitated a more comprehensive analysis of an interface’s usability problems. Finally, this approachalso afforded the added advantage of allowing the structured comparison of results after the evaluation wascomplete, allowing additional points to be uncovered.

3.4. Selection of electronic shops

Heuristic evaluation was applied to evaluate the user interfaces of four UK-based electronic supermarkets:Iceland, Tesco, Asda, and Sainsbury (Fig. 2), which are all popular supermarkets in the UK.

The decision to focus on category-specific electronic shops was taken so that they could be comparativelyevaluated. The rationale behind choosing electronic supermarkets as the focus for evaluation was thatsupermarket design requires careful consideration of many aspects, such as visual layouts, navigation routes,visual breaks, and attractive overviews of product groups (Mast & Berg, 1997), but past research has foundsupermarket interfaces to be problematic. In fact, research conducted into the usability of different genres ofelectronic shops has highlighted supermarket interfaces to be some of the worst examples. For example, astudy conducted by the Royal National Institute for the Blind (RNIB, 2001) found that supermarketinterfaces were considered as the least user-friendly of the genres evaluated (bank, fast food and clothing retailstores). Another study, conducted by Scott (2000), which examined the design of four supermarket web sites,criticised Sainsbury’s, Asda and Iceland raising major problems within their interface design and contentstructure. The only site that was praised was Tesco.

3.5. Evaluation procedures

The user interface for each electronic shop was considered in an alphabetical order. The evaluation for eachsupermarket interface was completed before moving on to the next one. The evaluations were split up intosmall sessions lasting up to two hours, each concentrating on a particular part of the interface. Two types ofevaluation technique were employed: free-flow and task-based inspections.

3.5.1. Free-flow inspection

The first part of the evaluation was a free-flow inspection. During each session, each interface was inspectedseveral times. The first pass allowed a general perception to be developed for the flow of interaction and thegeneral scope of the system. The second pass focused on the specific interface elements, whilst keeping in mindhow they fitted into the overall interface design. As each interface was examined, consideration was given towhether the specific interface elements adhered to or violated the extended set of heuristics and their specifiedcriteria. Problems outside the scope of the heuristics were documented, as were successful interface featuresthat worked well and those features that should not be changed. Each usability problem encountered, however

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Fig. 2. The sample page of each of the selected electronic supermarkets.


small, was listed separately and exemplified if needed, with the associated reasons and references to the specificcriteria and heuristic violated.

3.5.2. Task-based inspection

The second stage of evaluation was also split up into small sessions. The evaluation technique followed a usescenario, which comprised of the steps a user would usually take to perform a set of real tasks. These taskswere representative of the activities that a user would be expected to perform at an electronic supermarket.Examples of such tasks include the selection of products, booking delivery times, finding contact and helpinformation, and finally the checking out and payment processes.

In the same way as before, usability problems were documented as encountered whilst completing the abovetasks, and again with reference to the specific criteria and heuristic violated. Good design features andproblems outside of the scope were documented as well.

3.5.3. Severity rating

Once the preceding stages had been completed, severity ratings were assigned to the complete set ofevaluation criteria for each heuristic. This was done to indicate the relative seriousness of each problem inorder to facilitate decision-making and to help establish priorities. This method also served the purpose ofgaining additional insight into the usability problems and helped to direct the development of the guidelinesfor the future design of effective interfaces.

Three factors of severity were considered for each usability problem and combined into a single rating as anoverall assessment of each problem. These are outlined below:

�
The Frequency with which the problem occurred: Was it common or rare? � The Impact of the problem: Was it difficult or easy for users to overcome? � The Persistence of the problem: Was it a one-time problem that users could overcome or would users
repeatedly be bothered by it each time it occurred?

The purpose of considering the above factors when allocating severity ratings was to increase the accuracyof the ratings given. Taking into account the frequency, impact and persistence of each problem could help to


establish the correct priorities and to reduce the likelihood of making subjective judgements about theseriousness of the usability problems instead. The following scale was used for the severity ratings.

�

Ta

Th

He

Vis

Ma

Us

Co

He

Err

Re

Fle

Ae

He

Ski

Ple

Pri

To

0: Not a usability problem at all.
� 1: Superficial problem—fix if enough time available. � 2: Minor problem—low priority. � 3: Major problem—high priority. � 4: Usability disaster—imperative to fix.
The severity ratings were assigned after the evaluations had been completed, and not during the heuristicevaluation sessions. This was because the additional task of allocating severity ratings may have reduced theaccuracy of the estimates given by detracting from the main focus during evaluation, which was to find newusability problems. By allocating severity ratings after the sessions, there was a better understanding of theinterface’s problems as a whole, and the ratings given were more likely to be applied consistently.

4. Discussion of results

To conduct a comprehensive evaluation, both quantitative measurement and qualitative assessment wereapplied to analyse the results. The former used the final numeric results of the severity rating to identify theoverall effectiveness of each interface (see Section 4.1). The latter presented the documented successful featuresand problems from the free-flow and task-based inspections to illustrate in detail the strengths and weaknessesof each interface (see Section 4.2). These results were brought together to develop a more roundedunderstanding of current electronic supermarkets and were applied to develop usability guidelines to supportfuture improvements in the area (Section 4.3).

4.1. Quantitative measurement

The detailed quantitative results from the heuristic evaluations are presented in Tables 3–6. For eachheuristic listed, the number of criteria violated per severity rating has been shown. To be able to comparativelyevaluate the results from the heuristic evaluations, a weighting has been assigned to each heuristic. This hasbeen calculated by multiplying the number of criteria violated under each severity rating, by the severity ratingitself. The sum of these calculations was then added together for each heuristic to obtain the score in the ‘T’column in the tables. Higher scores indicate the most serious usability problems. By allocating scores in this

ble 3

e quantitative results for Asda

uristics Asda

0 1 2 3 4 T

ibility of system status 9 0 0 2 1 10

tch between the system and the real world 8 0 3 1 2 17

er control and freedom 7 0 1 1 5 25

nsistency and standards 13 0 0 1 1 7

lp users recognise, diagnose, recover from errors 4 2 3 2 2 22

or prevention 5 1 1 1 2 14

cognition rather than recall 10 1 2 2 1 15

xibility and efficiency of use 0 0 1 3 1 15

sthetic and minimalist design 3 2 1 0 0 4

lp and documentation 11 0 3 4 2 26

lls 5 1 2 3 0 14

asurable and respectful interaction with the user 6 0 0 1 1 7

vacy 2 0 0 1 0 3

tal 94 7 19 25 18 177

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Table 4

The quantitative results for Iceland

Heuristics Iceland

0 1 2 3 4 T

Visibility of system status 8 0 0 4 0 12

Match between the system and the real world 10 0 1 2 1 12

User control and freedom 9 1 1 3 1 16

Consistency and standards 9 2 1 2 1 14

Help users recognise, diagnose, recover from errors 9 0 4 0 1 12

Error prevention 4 1 1 2 1 13

Recognition rather than recall 13 0 2 1 1 11

Flexibility and efficiency of use 2 0 3 0 0 18

Aesthetic and minimalist design 4 0 2 0 0 4

Help and documentation 11 0 2 7 0 25

Skills 6 0 4 0 0 8

Pleasurable and respectful interaction with the user 4 5 0 2 0 11

Privacy 3 0 0 0 0 0

Total 99 10 24 27 7 179

Table 5

The quantitative results for Sainsbury

Heuristics Sainsbury

0 1 2 3 4 T











Skills 8 0 2 1 0 7


Privacy 1 0 0 0 2 8

Total 113 7 25 9 11 128


way, it was easier to determine the specific categories of usability problems that caused the most concern foreach interface, and to highlight recurring usability problems for all of the interfaces evaluated.

By adding the scores in the ‘T’ column together for each of the interfaces, an overall assessment could bemade of the usability problem of each interface. Tesco was the worst example with a total score of 242. Icelandand Asda came next with scores of 179 and 177 respectively. The interface with the fewest usability problemswas found to be Sainsbury’s with a score of 128.

4.2. Qualitative assessment

As described in Section 3, each heuristic had specified criteria that were used for conducting the free-flowand task-based inspections. During the inspections, the problems and successful interface features weredocumented; the most frequently recorded successful interface features were regarded as strengths and the

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Table 7

The qualitative results for Asda

Heuristics Asda

Strengths Weaknesses

1. Visibility of system status During tasks, users can always tell how

much more/longer there is to go

The system does not tell the user the state

of the system and the alternatives for

action

2. Match between the system and the real

world

Icons are easy to identify and needed The system does not anticipate the user’s

expectations at each step

3. User control and freedom Users can easily reverse actions No undo function for action/group of

actions. Users cannot set up their own

defaults

4. Consistency and standards Consistent formatting standards have been

applied throughout the site

Vertical and horizontal scrolling can work

in all windows

5. Help users recognise, diagnose, recover

from errors

Prompts are brief and constructive Error messages do not provide

appropriate semantic information

6. Error prevention Fields in data entry screens and dialogue

boxes contain default information when

appropriate

Users are stuck if a sensor ‘breaks’

7. Recognition rather than recall The same colour is used to group related

elements

Prompts, cues and messages are not

obvious

8. Flexibility and efficiency of use None Users cannot be interrupted at any time

9. Aesthetic and minimalist design Each screen has a short, clear, distinctive

title

Some irrelevant information is displayed

on screen

10. Help and documentation It is easy to access and return from the

help system

The help system interface is inconsistent

with the rest of the site

11. Skills The system performs data translations for

users

The help system interface is inconsistent

with the rest of the site

12. Pleasurable and respectful interaction

with the user

Colour is used with discretion Excessive window housekeeping required

13. Privacy None Password functions are ineffective

Table 6

The quantitative results for Tesco

Heuristics Tesco

0 1 2 3 4 T











Skills 6 1 2 1 1 12


Privacy 0 0 0 0 3 12

Total 74 4 32 24 25 242


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Table 8

The qualitative results for Iceland

Heuristics Iceland


1. Visibility of system status The user can easily determine where they

are and what options are available

During tasks, users cannot tell how much

longer there is to go


world

Required inputs are meaningful Task/menu choices are not ordered in the

most logical way

3. User control and freedom For multiple menu levels, a mechanism

allows users to go back to previous menus

No undo function for action/group of

actions. Users cannot easily reverse their

actions

4. Consistency and standards Standards have been applied to interaction

design

The pages layouts are not consistent


from errors

If an error is detected in a data entry field

the system highlights the field in error

Error messages do not provide


6. Error prevention Fields in data entry screens and dialogue

boxes contain default information when

appropriate

Menu choices are not logical and

distinctive

7. Recognition rather than recall All the data a user needs is on display at

each step in a transaction sequence

Mapping between controls and actions is

not apparent to users

8. Flexibility and efficiency of use Partially filled screens can be saved Multiple levels of detail are not available

to support novice and expert users

9. Aesthetic and minimalist design Only information essential to decision

making is displayed on screen

Not every screen has a title

10. Help and documentation The information in the help section is

complete, accurate and understandable

Users cannot easily switch between help

and their work

11. Skills Important keys are larger than other keys Multiple levels of detail are not available

for novice and expert users


with the user

Colour has been used with discretion Excessive window housekeeping required

13. Privacy Protected areas are completely inaccessible None


most frequently encountered problems were considered as weaknesses. Tables 7–10 present the key strengthsand weaknesses of the interfaces of each electronic supermarket arising from of the qualitative assessment.

To summarise the qualitative results, the common strengths and weaknesses for the entire electronicsupermarket interfaces evaluated are outlined below.

4.2.1. Common strengths

�
Aesthetic and minimalist design: For most of the interfaces evaluated, only essential decision-makinginformation was displayed on each screen. Icons were usually distinct and each screen had a clear title.White space had been used effectively for justification, and field and menu titles were mostly brief, yet longenough to communicate the key issues.
�
Pleasurable and respectful interaction with the user: Colours had been used effectively in most of theinterfaces. Colour schemes were generally simple and had been consistently applied throughout the sites.Colours had been used effectively to draw attention, communicate organisation, indicate status changesand establish relationships. The most frequently used function keys were mostly located in the easilyaccessible positions.
4.2.2. Common weaknesses

�
User control and freedom: Users were often not free to select and sequence tasks according to theirown personal preferences. There was a lack of clearly marked emergency exits to leave an unwanted

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Table 9

The qualitative results for Sainsbury

Heuristics Sainsbury


1. Visibility of system status The user can easily determine where they

are and what options are available

When the system response is delayed, users

are not kept informed of the system’s

progress


world

Task/menu choices are ordered in the most

logical way

System does not anticipate user’s

expectations at each step

3. User control and freedom For multiple menu levels, a mechanism

allows users to go back to previous menus

No undo function for action/group of

actions

4. Consistency and standards Online instructions appear in a consistent

location across screens

Optional data entry fields are incorrectly

marked


from errors

Prompts are brief and constructive Error messages do not provide


6. Error prevention Data entry fields contain default

information when appropriate

Menu choices are not logical and

distinctive

7. Recognition rather than recall Different colours are applied to identify

emphasised data and de-emphasised data

None

8. Flexibility and efficiency of use The system provides options for high-

frequency commands

None

9. Aesthetic and minimalist design Only information essential to decision

making is displayed on screen

None

10. Help and documentation Additional explanatory information is

provided when ambiguous menu choices

are selected


and their work

11. Skills The different options were provided None


with the user

Very effective use of colours None

13. Privacy Protected areas can be accessed with

certain passwords

None


state without having to go through an extended dialogue. Undo and Redo functions were hardly eversupported.

�
Help and documentation: It was not easy for users to switch between help and their work and to carry onfrom where they left off. There was also a lack of context-sensitive help. The help interfaces were ofteninconsistent with the rest of the system.
5. Development of guidelines

Based on the findings from the inspections, a framework of usability guidelines was developed for the futureimprovement of the usability of electronic supermarkets. Guidelines were generated for each heuristic and theyreflected both the common usability problems encountered by users in the study and good design featuresidentified. Each guideline contains two parts. The first part is the specific ‘interface considerations’ that shouldbe followed when developing an electronic shopping interface and the second part outlines the ‘purpose’ ofincorporating each interface consideration into the design. In effect, the former indicate ‘what’ interfacefeatures should be considered in electronic supermarket Web sites and the latter explain ‘why’ these featuresare critical. The full list of guidelines is presented in Table 11.

To implement the guidelines successfully, senior managers responsible for the electronic supermarketsneed to develop a strategic plan, in which user-centred design of the Web site is an essential issue. Inother words, there is a need to involve users in the implementation process, which may include the followingactivities.

ARTICLE IN PRESS

Table 10

The qualitative results for Tesco

Heuristics Tesco


1. Visibility of system status Colour coding issued to depict the selected

options

Users cannot easily identify where they are

in the interaction process


world

Questions are always stated in clear,

simple language

Users would be taken through a

mandatory registration step

3. User control and freedom There is a mechanism that allows users to

go back to previous menus

Some commands have severe, destructive

consequences

4. Consistency and standards Standards have been applied to interaction

design

Different formats are applied in different

sections of the site


from errors

None Error messages do not provide


6. Error prevention Data Inputs are case-blind where possible Less important options are not located in

the least convenient positions

7. Recognition rather than recall The same colour is used to group related

elements

Prompts, cues and messages are not placed

in the obvious position

8. Flexibility and efficiency of use System provides options for high-

frequency commands

There are no multiple levels of detail to

support novice and expert users

9. Aesthetic and minimalist design Each screen has a short, clear, distinctive

title

Extraneous information is displayed on

screen

10. Help and documentation The help section is complete, accurate and

understandable


and their work

11. Skills The system performs data translations for

users

Users are responders rather than initiators

of actions


with the user

Minimal window housekeeping required Abundant use of colour and excessive icon

design

13. Privacy None Password functions are ineffective


�
Designers of the Web site of the electronic supermarkets need to explain the guidelines to the users and askthem to check whether these guidelines match with their requirements. The value of the guidelines rests intheir utility as points of reference rather than as inflexible standards. Therefore, the designers shouldcarefully consider the users’ feedback to revise the guidelines and reflect on their instantiation in the designof specific Web sites.
�
The revised guidelines can be used for the evaluation of the existing electronic supermarkets. After theevaluation, two alternative design options can be considered. One is to produce a ‘new’ interface for theelectronic supermarket and the other one is to produce a ‘redesigned’ interface based on the existingdesign. The final decision of which option to follow may well depend on how many problems arediscovered.
�
Designers could develop a prototype first to address any problems found with an existing Web siteand conduct user testing of the prototype, the results of which can be used to improve the prototypeand (after subsequent cycles of iterative improvement if finances allow) to implement the finalinterface.
�
It can take some time for users to accept changes, so both the old and new interface might be provided inthe first three months alongside a brief description to explain the differences between the two to informusers and help them to choose freely which interface they want to use. The users’ choices and their buyingbehaviour can be recorded in a log file, which will be used to analyse whether the new interface can increasethe users’ purchase and to better understand any resistance to change. In addition, surveying might help toidentify whether user satisfaction can also be improved by providing the new interface. These results can beused to evaluate whether the new interface is effective and to highlight improvements that might need to beconsidered at the next stage.

ARTICLE IN PRESS

Table 11

Usability guidelines

Euristics Interface Considerations Purposes

H1: visibility of system

Status

To highlight current option selected To identify current location in interaction process

To breakdown steps required to complete tasks, and

highlight current step reached in interaction process

During all tasks, to indicate to users how much more/

longer there is to go

To display all options pertinent to the users tasks

during interactions

At every time during the interaction, to indicate to

users what options are available and the alternatives

for action

To display messages if observable delays are longer

than 10 seconds

To keep users informed of the systems progress

H2: match between the

system and the real world

To provide easily identifiable icons when needed To make information easy to remember and identify

To use clear, simple language for question and

answer

To make information easily understandable for users

To arrange task/menu choices in a logical order

according to natural sequences

To decrease cognitive load on users

To provide meaningful menu choices To allow menu choices to be readily understood

H3: user control and

freedom

To provide mechanism for multiple menu levels To allow users to go back to previous menus

To provide undo functions for every action/group of

actions

To allow users to reverse their actions and change

earlier choices

To provide back options on every page where a user

is completing tasks

To give users the freedom to select and sequence their

own tasks where possible

To provide users with customisation of system,

session and screen defaults

To allow users to set their own preferences

H4: consistency and

standards

To follow company formatting standards To maintain consistency throughout the site

To match menu structure to task structure To reduces cognitive load on user

To provide vertical/horizontal scrollbars in all

windows

To allow all information in every window to be

viewed

To follow consistent standards for interaction design To facilitate easy interactions with the system

To use consistent location for online instructions To help users easily find instructions

H5: help users recognise,

diagnose and recover

from errors

To show meaningful error messages To suggest the causes of the problems

To provide suggestion actions when users make

errors

To allow users to recover from the error

To show constructive, brief, unambiguous messages To imply that the user is in control

To highlight the field in error in data-entry fields To attract attention on the particular field in error

H6: error prevention To provide default values when users fill out the

forms

To reduce the likelihood of errors occurring

To put less frequently used options in least

convenient positions

To use the screen effectively

To show way out for users to exit the system To ensure users cannot get stuck

To put function keys causing serious consequences

far way from low consequence and high-use keys

To prevent errors

To show warning message if users are about to make

serious error

To make sure user has not selected an option in error

H7: recognition rather

than recall

To group items in logical zones with headings To distinguish between different groups of items/

zones

To place prompts where eye is likely to be looking To make prompts clearly visible to users

To use colours to group related elements To distinguish between groups of elements

To distinguish emphasise data and de-emphasise data

with different colours

To draw attention to important data. To make less

important information not distractive


ARTICLE IN PRESS

Table 11 (continued )

Euristics Interface Considerations Purposes

H8: flexibility and

efficiency of use

To allow user to save partially filled forms To allow flexibility for users to return to their work at

a later time

To provide multiple levels of detail To cater for the different needs of novice and expert

users

To allow tasks to be resumed after a short period of

time

To allow users to go back to their tasks when they are

interrupted

To provide shortcuts for high-frequency actions To speed up interaction for users

H9: aesthetic and

minimalist design

To display only essential decision-making

information on screen

To increase visibility of essential information

To show brief and clear title for each screen To make immediately apparent the nature of content

within each screen

To separate meaningful groups of items by using

white space

To increase visibility of different groups of items

H10: help and

documentation

To maintain consistent help system interface To ensure consistent standards applied throughout

the site

To provide option to switch between help and work To allow users to easily switch between help and their

work

To provide additional explanatory information for

ambiguous options

To provide further help where it is most likely to be

needed without having to search through the help

system

To allow work to be resumed from where left off after

accessing help

To anticipate the users’ expectations

H11: skills To make important keys larger than other keys To make important options highly visible

To anticipate users’ next activity correctly To anticipate users’ expectations

To allow users to initiate actions To ensure users can actively take actions rather than

respond to them

H12: pleasurable and

respectful interaction with

the user

To make discretionary use of colour To enhance quality of users interactions with the

interface

To require minimal window housekeeping To reduce the level of extra work for users

To use colour us to draw attention, communicate

organisation and status changes

To enhance quality of interactions with the systems

H13: privacy To make protected areas inaccessible To protect users’ personal and confidential

information

To make protected areas accessible through

passwords

To give each user access to their own personal

information

To make use of effective password features To ensure user confidence and trust


6. Concluding remarks

This study has applied Nielsen’s heuristics (1994) to examine the interface design of electronic shopping,especially for electronic supermarkets. The evaluation results suggest that the interface design of currentelectronic supermarkets needs to be improved. The most significant and common usability problems werefound to lie within the boundaries of the heuristics ‘User Control and Freedom’ and ‘Help andDocumentation’. For example, with regard to user control and freedom, users were not free to sequencetheir own tasks, and undo and redo functions were not supported. There was also a lack of clearly markedemergency exits for users to leave an unwanted state. For help and documentation, a recurring problem wasthat users were not able to switch between help and their work and carry on from where they left off. Therewas also a clear lack of context sensitive help, and the help system presented in the interfaces was inconsistent.These results suggest that the designers do not pay enough attention to usability issues associated withelectronic supermarkets and/or that they lack the expertise to develop consistently usable interfaces. There is a


need to provide guidance for them to integrate the usability considerations into the development of electronicshopping sites. Thus, this study developed a support mechanism for the design of electronic shopping in theform of usability guidelines. This mechanism can be used to support designers in evaluating whether or not aninterface is desirable based on whether it meets these guidelines, with the final goal being to create effectiveelectronic shops that can meet with users’ needs and increase their shopping enjoyment and the value of theirpurchase.

However, this study is only a small step. Nielsen (1993) suggested that heuristic evaluation does not allow away to assess the quality of redesigns; the best results can often be found by alternating both heuristicevaluation and user testing. Future research could conduct user testing to assess the robustness and reliabilityof the usability guidelines suggested by this paper, which could ensure in turn the development of ‘user-centred’ interfaces to electronic shops. Therefore, it would be valuable for future research to see whetherelectronic shopping applying the proposed usability guidelines can increase the satisfaction of the customers orwhether their satisfaction would be same. In addition, previous research has indicated that individualdifferences have significant effects on users’ perceptions of the interface features (Chen & Macredie, 2002;Chen, Magoulas, & Macredie, 2004). This suggests that there is also a need to conduct further research toexamine how individual differences influence the ranking of interface considerations proposed by theguidelines in this paper. The findings of such studies could be applied to build a robust user model for thedevelopment of personalised electronic shopping sites that could accommodate users’ individual differences.

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Sherry Chen obtained her PhD from the University of Sheffield in 2000. Currently, she is a Senior Lecturer in the School of Information

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